Pneumatic ophthalmic-chart cabinet.



PATBNTED JULY 18,- 1905. L. 0. BISANG.

PNEUMATIC OPHTHALMIC CHART CABINET.

APPLICATION FILED FEB. 17. 1905.

Elvwwwfoz NEIHLSTU UNITED STATES Patented July is,19o5.

PATENT OEEicE.

PNEUMATIC OPHTHALMIC-CHART CABINET.

SPECIFICATION forming part of Letters Patent No. 794,918, dated July 18, 1905,

Application filed February 17, 1905. Serial No. 2%,072.

To all whom it may concern:

Be it known that I, LOUIS O. BISANG, acitizen of the United States, residing at the city and in the county of San Francisco and State of Oalifornia,have invented new and useful Improvements in Pneumatic Ophthalmic-Chart Cabinets, of which the following is a specification.

My invention relates to an apparatus especially designed for use in connection with optical practitioners.

It consists of a polygonal drum turnable upon a shaft upon which it is carried and a pneumatically-actuated device by which the drum may be advanced to expose its sides successively, said sides having characters marked thereon which are designed to test the condition of a patients eyes.

My invention consists in details of construction, which will be more fully explained by reference to the accompanying drawings, in which- Figure 1 is a front view. Fig. 2 shows the movable parts separated from the case. Fig. 3 is an enlarged side elevation of operative parts and section of revoluble polygon. Fig. 4 is an edge view of same. Fig. 5 is a perspective view of advancing and check ratchet. Figs. 6 and 7 are views showing the pawl to prevent backward movement.

Aisacase of anysuitable construction, within which my apparatus may be conveniently located. The up per part of the case may have marked upon it lines radiating froma central point and figures marked thereon, as shown at 2, such lines being designed to primarily test the condition of a patients eyes. Below this plate is an opening, as at 3, of sufficient dimensions to expose the sides of the polygonal drum 4L. This drum has its shaft suitably journaled within the case A, and the faces of the drum have white enameled or other plates fixed upon them by means of clamps 5 at the angles of the polygon, so that the plates may be readily removed or others substituted at will. Upon one end of the shaft of the drum is fixed a ratchet-wheel 7. Apawl 8 is mounted upon a lever-arm 9, so as to engage the ratchet, and when the lever-arm is moved the pawl will advance the ratchet a tooth, and thus turning the shaft will turn the polygon so as to expose either of its sides having characters marked thereon through the aperture in the casing.

The mechanism for actuating the device consists of a cylinderlO, having a piston-rod extending out through one end of the cylinder and connected, as shown at 11, with a vertically guided and movable slide 12. The crank or lever arm 9, which carries the pawl 8, is slotted to allow it to move in the arc of a-circle and is connected by a pin 13 through a slot with the slide 12, so that when the slide is moved in one direction it will turn the lever-arm and with it the pawl to turn the ratchet-wheel and the drum. A spring, as at 15, serves to return the parts to their normal position after a forward impulse. This forward impulse is effected by means of a column of air conducted through a tube, as at 16, from a pressure-bulb or equivalent device, as at 17. The tube is of considerable length, so that the operator, holding the tube in his hand, sitting at the side of the patient, will be located at such distance as is required for the tests to be made upon the eyes. Thus, the patient being seated at the proper distance from the apparatus, by a pressure upon the bulb the column of air conveyed through the tube 16 acts upon the piston within the cylinder and the polygon carrying the various-sized characters or letters upon its faces is turned to bring the first test characters into view. From this point as the operation proceeds the polygon is turned each time to expose a new face until the op erator has ascertained the condition of the patients eyes.

In order to prevent the backward movement of the polygon and to hold it with the face properly exposed, I have shown a springlatch, as at .19, adapted to engage with notches or stops upon the end of the cylinder, and in order to prevent the revolution of the polygon too far by reason of the impulse I have shown a latch or pawl 20 so pivoted as to be actuated by the upward movement of the piston and connected parts, and this pawl is engaged with a ratchet which limits the forward revolution of the cylinder, while the catch previously described prevents its moving backwardly.

The pawl 20 is disengaged from its ratchet by the return movement of the parts, so as to leave the cylinder free to be again advanced.

To make the operation of the pawl fully understood, I will state that when the slidable bar 12- is raised by the impulse of the piston and its rod the crank or lever arm 9 is moved upward about its center, and through the pawl 8 engaging the ratchet 7 upon the shaft ofthe drum or polygon the latter is revolved. As the drum is of considerable weight, it is necessary to prevent its momentum from carrying it too far. Therefore, as shown in Fig. 4, I employ pins 7, projecting from the back of the ratchet 7 and these pins are in the path of the hook-shaped end of the pawl 20, which is tilted by contact of the projecting end of the pin 13, or an equivalent, so that just at the end of the upward stroke and the advance of the polygon by the pawl 8 the pawl 20 will be thrown down to engage one of the pins 7, and as the abrupt check might cause the polygon to rebound and swing back the pawl or catch 19 at the same instant engages one of the holes in the opposite end to prevent such backward oscillation.

Having thus described my invention, what 1 claim, and desire to secure by Letters Patent, is

1. An ophthalmic chart consistingof a horizontally-journaled polygon having test characters removably secured upon its faces for testing purposes, a containing-casing having an opening through which the polygon-faces may be singly and successively exposed, a pneumatically-actuated mechanism by which the polygon may be intermittently revolved to expose its faces.

2. An ophthalmic chart consisting of a horizontally-journaled revoluble polygon having test letters or characters removably secured upon its faces, ;an inclosing casing having an opening through which said faces may be individually and successively exposed, a ratchet mounted upon the polygon-shaft, a pawl engaging the ratchet, a pneumatic cylinder having a piston movable therein, a compression-bulb and tube through which air may be delivered to the cylinder and mechanism connected with the piston by which the pawl is moved to rotate the polygon.

3. An ophthalmic chart consisting of a horizontally-journaled polygon, removable plates having test letters and characters marked upon their faces, acasing having-an opening through which said faces may be successively exposed, a cylinder havinga plunger movable therein, a plunger-rod extending through the end of the cylinder, aguided slide connected with the rod, a lever-arm loosely mounted u pon the polygonshaft having its outer end connected with the slide, a pawl carried by the lever-arm and a HGSSGS.

ratchet upon the polygon-shaft engaged by the pawl, a tube extending from the cylinder to the operators position, and a bulb wherebycompressed air may be forced into the cylinder and the mechanism moved to revolve the chart.

4. An ophthalmic chart consisting of a polygon, plates removably fitted to the sides of the polygon and provided with test letters and characters, a casing through which they faces are successively exposed, a pawl-andratchet mechanism, a pneumatic cylinder, connections between its plunger-rod and a pawlcarrying lever whereby the reciprocation of the plunger within the cylinder is transmitted to advance the polygon to expose a new section and its face, a latch engaging the polygon to prevent its return movement, a tube connecting with the cylinder and a compressionbulb controllable by the operator to force air into the cylinder and operate the apparatus.

5. An ophthalmic chart consisting of a horizontally-journaled revoluble polygon having plates removably fitted to its sides and provided with test letters and characters upon its faces, a casing having an opening through which the faces are successivel-5.1...exposed,a

ratchet-wheel fixed to the polygon-shaft, an oscillating lever carrying a pawl which engages the ratchet, a cylinder having a pneumatically-actuated piston, a guided slide with which the piston-rod and pawl-carrying lever are connected to advance the polygon at each impulse and a spring by which the parts are returned to their normal position when the impulse ceases.

6. An ophthalmic chart consistingof a horizontally-revoluble polygon, the faces of which have test letters and characters marked thereon, a casing having an opening through which the polygon-sides are successively exposed, a pneumatic cylinder, a tube connecting with the cylinder and a bulb through which air is forced to move the piston, a guided slide connected with the piston having a spring by which it is returned after the impulse has ceased, a ratchet-wheel fixed to the polygonshaft, an oscillating lever-arm loose upon the shaft having the outer end connected with the slide and a pawl carried by the arm to engage the ratchet, a second pawl actuated by the movement of the piston and engaging a ratchet to limit the forward movement of the polygon, and a second spring-actuated latch to prevent a return movement of the polygon.

In testimony whereof I have hereunto set my hand in presence of two subscribing wit- LOUIS O. BISANG. Witnesses:

S. H. NQURSE, HENRY P. TRIooU.

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